A related art phase array antenna uses an electrical microwave phase shifter for steering beam in a desired direction, and in this case, there is a beam squint problem where the phase array antenna is usable in only a narrowband due to a phase error caused by a frequency of a phase shifter.
In phase array antennas, it is required to develop beamforming technology for causing a desired phase shift regardless of a frequency of a radio frequency (RF) signal in order for the phase array antennas to be used even when the frequency of the RF signal varies rapidly or transmission of a wideband signal is needed.